Waterproof abrasive article



Oct. 3,1939. H. R. sTRATFoRD 2,174,902

WATERPROOF ABRASIVE ARTIICLE Filed May 2l, 1937 1N VENTOR.

ATTO EYS Patented Oct. 3, 1939 wA'rERrnoor ABnAsrvE Annota Herbert R.. Stratford, Cleveland, Ohio, assignor to The Stratmore Company, Wilmington, Del., a corporation of Delaware Application May 21, 1937, Serial No. 143,972

3 Claims.

the provision of a disk for this purpose which shall be long-lived', capable of severe service against such surfaces as welds between metal sheets and also capable of being employed with a liquid applied to the surface being operated upon to prevent the contamination of the surrounding air by particles either of abrasive or of the surface being abraded. Although my improved disk.

is particularly adapted for use in wet surfacing e operations it is also capable of use in dry work and has shown very satisfactory life and service therein.

To the accomplishment of the foregoing and related ends, said invention, then, consists of the means hereinafter fully described and particular- 1y pointed out in the claims; the annexed drawing and the following description setting forth in detail certain ystructure embodying the invention, such disclosed structure constituting, however, but one of various structural forms in which the principle of the invention may be used.

In said annexed drawing: Fig. 1 is a side elevation of a portable surfacin apparatusof well-known type, to which is applied one form of my yimproved disk, the disk and means .directly supporting the same being shown in central section;

Figs. 2, 3 and 4 are partial transverse sections through various forms of my improved disk;

Fig. 5 is a partial transverse section showing one form of my. improved disk and, in dotted lines, the position of the outer portion of the same when in action;

Fig. 6 is a View similar to Figs. 2, 3 and 4, but showing another modification of the disk construction; and

Fig. 'I is a similar view showing still another modication.

In the finishing of steel automobile bodies it is `lnow common practice to butt-weld sheets of steel, thus producing a homogeneous continuous joint along the abutting edges of the sheets, but also producing a fln or bur on the weld and in some cases a recess or groove. The burs are ground away. by portable surfacing machines employing flexible abrasive disks of the type described and claimed in the Stratford Patent No.

ting sheets is depressed it has been found neces- 1,686,938 and the Carlton Reissue Patent No. 20,946 and these disks have been found highly satisfactory for this purpose aswell as for many other uses in various industries.

In cases where the seam or joint between abutsary to run into the depression a small amount of a low-melting-point metal, such as solder, lead and the like, and then grind down the resulting irregular strip of solder to the level of the adjoining surfaces. If this operation is carried out in the dry state, particles of lead are tlnjown into the air and representa distinct hazard to the workers through lead poisoning. In order to prevent the contamination of the air it is very desirable to apply a liquid to the surface which is being abraded by the surfacing disk, but whether oil, water or similar material is applied, the ordinary disks of the type described in the patents referred to above become soaked and lose 20 their strength so that 'they can be used only a relatively short time. To meet this condition I have invented a new composite disk which is resistant to such liquids as oil, kerosene, water and the like, retainingits strength and cutting 25 ability when used against' such surfaces when applied. In addition to being of extreme valuable service under these conditions I have found that this disk is superior to the ydisks of the types referred to above for certain dry sanding operations, in that they are thicker, give similar-cutting action of a grinding wheel and have a very considerably longer life'under the sameconditions. l

In Fig. l I have shown more or less diagrammatically a portable surfacing tool, consisting of 'a casing l provided with handles 2 and 3 for convenient manipulation byl an operator and having a shaft extending from its bottom. The shaft 4 is rotated by means of gears, which are not shown, enclosed within the head and driven either by a flexible shaft which can be carried into the interior of the `casing l through one of the hollow handles 2 or by a self-containedfair or electric motor housed in the casing I. Tools of this general character are in use in many industries to the extent of many thousands and A need not be described in further detail.

Fixed to the shaft I is a hub5 and means for supporting the abrasive element in the form of a compressible and slightly flexible pad 6 which is in turn supported by lapped metallic resilient plates l, 8 and 9. It will be understood that a varied number of supporting plates may be employed behind the compressible and flexible pad means which may be employed with my improved disk. Beneath the supporting pad 6 and in contact with its lower surface is the abrasive disk I0, the construction of which will be presently described, which is coextensive in diameter with the supporting pad and is secured to the driven shaft 4 by means of a removable nut I I.

My improved diskconsists of a composition of a phenol resin condensation product and abrasive thoroughly intermixed therewith, the disk being shown, for example in Fig. 2. The disk I0 is of material thickness, as indicated in Fig. 1, and consists of abrasive material intermingled with and bonded into a phenol resin condensa.-4

tion product to produce a homogeneous disk which is substantially a disk of the character now manufactured and employed as a so-called cut-off wheel, except that on the face which is against the pad 6, the disk is flrst provided with a layer of reinforcing material, which may be a textile such as canvas I3, which will assist in reinforcing the article'and preventing breakage and throwing oif of broken particles. The exact composition of the disk will depend of course upon the nature of the work for which it is designed, but for operations upon welds a mixture of abrasive and resin approximating-that now employed in cut-off Wheels has been found satisfactory and givesv a product which has suflicient iiexibility out of its normal plane to accommodate itself to the slight flexure required in severe sanding operations.

In Fig. 2 the reinforcing sheet, here shown as canvas, is shown secured to the disk proper by means of the adhesiveness of the phenol resin, the canvas being laid in the mold and molded to the disk during its formation.

In Fig. 3 a canvas sheet is shown secured to the disk proper by an intermediate layer of adhesive I4, such for example as rubber cement or similar material.

In Fig. 4 I have shown a composite disk in which separate layers I5, I6, I1 and I8 are secured together to produce a single composite disk, the layers being separated but secured together by layers I9,20 and 2l of a textile material, such for example as canvas, which may be molded into the disk as formed. These layers will serve to very considerably reinforce and strengthen the disk, particularly against the action of centrifugal force during wear, While the layers of material will be rapidly worn away against the surface after all of the materialiis worn off, exposing the layers. f

In Fig. 6 I have shown a pro'led disk 22, in

,which the outer portion is thicker than the cen- Ill and, in dotted lines, the deflection of which the disk is capable to accommodate itself to the pressure against the work.

The present disk is distinguished from abrasive disks now in general use and of the type referred to hereinabove by being substantially a self-supporting disk or wheel employed, however, to operate upon the work with its at surface instead of its edge. It is entirely waterproof and can be used for relatively long periods in the same general service as coated abrasive disks of the types now in use, and, when its long life is taken into account, its higher cost compared with that of a single abrasive coated disk is not excessive.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the structure herein disclosed,V provided the means Astated by any of the following claims or the equivalent of such stated `means be employed.

f I therefore particularly point out and distinctly K claim as my invention:

l. A disk of the character described comprising a relatively rigid disk formed of a phenol condensation product uniformly impregnatedl with abrasive particles, the outer portion of said disk being thicker than the central portion thereof, and having a working surface of substantial area, which lies in a plane normal to the axis of the disc.

2. A disk of the character described comprising a relatively rigid disk formed of a phenol condensation product uniformly impregnated with abrasive particles and provided with a reinforcing sheet of textile material, the outer portion of said disk being thicker than the central portion thereof, and having a working surface of substantial area, Which lies in a plane normal to the axis of the disc.

3. In surfacing apparatus, the combination' of a shaft, a supporting pad secured thereto having its central portion resistant to axial displacement but having its radially outer portion slightly displaceable axially upon pressure being applied thereto in an axial direction, and a relatively rigid composite abrasive wheel also secured to said shaft and supported by said pad, said wheel being formed of a phenol condensation product uniformly impregnatedv with abrasive particles and having its radially outer portion axially displaceable a distance equal to its thickness upon application of axial pressure thereto.

HERBERT R. S'I'RATFORD. 

